Can someone point me to where can I get BMW rim style 270 for an 2011 M3 sedan, other than dealers? I am looking to see how much will I need to spend on a set of winter tires and rims and the dealer I work with quoted me CAD 3800+tax for these rims and Michelin Pilot Sport Alpin PA3 tires.

A few tips:
- check the wheel and tire technical subsection for more winter wheel/tire info
- check the wheel and tire for sale subsection for lots of 18" wheels for sale
- a few dealers/forum sponsors sell OEM stuff for way better pricing than Canadian dealer pricing, and will ship.
- consider low-cost aftermarket wheels for your winter setup - VMR, Alufelgen, etc. - in either 18 or 19" fitments.
- peruse TireRack for some further options and more info.

Depending on your location in the Great White North, PA3s may not be the recommended winter tire of choice for our M3s. See above for more info. And don't forget to SEARCH the forums - there are LOTS of informative winter tire threads.

In addition to what Chowster just said, I'll be frank and add this: please just skip the winter-specific 270M wheels entirely, and go with a set of 219M or 260M. You can get these used for $1000 give or take, and they will be great for the winter. If you want a non-staggered setup like the 270M, simply get four front wheels instead of the 8.5" front and 9.5" rear that the stock summer setup provides.

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A gen-u-ine BMW eff-eight-zero with them tandem clutches in the transmission and that dad gum sun roof on the top-a da cawr.

I thought about using four front wheels as a winter setup. However, my calculations were that the fronts on the rears ought to have something like a 15mm spacer.
In the end I went with standard staggered. 18" wheels but with 235/40 PA3 tires all round. That is within the Michelin specs.